The present invention relates to industrial trucks, and more particularly, to a compact industrial truck including both a fork lift assembly and a coupler carried at least at one end of the chassis for coupling a trailer to the truck independently of the fork lift assembly.
A great variety of industrial trucks equipped with fork lift devices have been proposed, ranging from relatively large four-wheel electric fork lift trucks of the general type disclosed in Schenkelberger U.S. Pat. No. 3,148,871 to compact fork lift trucks having a steering arm-controlled power traction unit and a fork lift apparatus extending from the body of the truck adapted for being controlled by an operator standing adjacent the truck, as disclosed in Gibson U.S. Pat. No. 2,942,679. Representing an intermediate range of fork lift trucks including a platform upon which an operator may stand while operating the truck is the apparatus disclosed in Ayers U.S. Pat. No. 2,885,016.
Electric or internal combustion engine-driven industrial trucks of this general character have been also used heretofore for pulling a trailer, or a string of trailers, by coupling the same to one end of the truck in one or another of different ways. For example, representative of the disclosure of such units are the U.S. Pat. Nos. to Ulinski 3,074,500; Christensen 3,944,258; and Burger et al 1,715,815.
A small, compact industrial truck known as a "tugger" and suited for having one or more trailers couplere thereto is commercially available from the Clark Company, Industrial Truck Division, Battlecreek, Michigan, 49016 and sold under the registered trademark "Powrworker," e.g., as models 2T-18/2T-18/2THS-12-24. Trucks of this type include a short chassis having a battery-driven electric motor unit at the front of the chassis including a single traction wheel steered by a steering arm manipulated by an operator standing either on a platform at the rear of the truck or on the ground adjacent the device by virtue of a pivotal connection of the steering arm, thereby permitting the arm to be used for control of the truck when the operator is either riding or walking. The end of the steering arm has fingertip controls for controlling forward and rearward movement of the truck. Such tuggers have a coupler at the rear of the truck for coupling of the trailers to the truck.
However, none of these patented or commercial prior art devices effectively combine the advantages of a small, compact industrial tugger with the capability of a fork lift truck for lifting of palletized loads, and while retaining such compactness, permit an operator to control the device either from a platform on the truck of from a position adjacent the unit via use of a walking beam-type steering arm. Moreover, none of the previously known configurations provide control features which could be incorporated in a truck having such a combination of a fork lift assembly and a coupler at one end of the truck chassis so as to permit facile control of both movement of the truck as well as raising and lowering of the forks bearing in mind that movement of the truck necessarily might have to be in either direction.
Characteristically, fork lift trucks are driven with the tines or forks of the fork lift assembly oriented in a forward direction since the operator typically faces toward such forks, and it is more convenient to operate the truck in the direction in which the operator is compelled to stand or to sit while manipulating the controls. On the other hand, for the reasons of safety, it would be quite desirable to operate the truck with the fork facing rearwardly, not only because such arrangement would be less likely to impale pedestrians upon the forks or to strike such pedestrians with loads carried thereon, but also because braking of the truck would not tend to dislodge the load from the forks but rather would ensure that the load remains seated upon the forks in a stable configuration.